Contrasting with ordinary jurisdiction, confidentiality has been construed as one of the inherent advantages to arbitration and constitutes one of its more significant myths. Nevertheless, beyond the cliché of confidentiality as one of the more useful features of arbitration, practice make us question whether we are facing a fiction more than a reality. Most of the times, arbitration confidentiality is more of a presumption of the arbitrators, arbitral institutions or of the parties when it has not been expressly recognized in the arbitral clause, and it is not possible to find an unequivocal answer to that presumption. On the contrary, national regulations – with the curious exemption of Spanish law (art. 24.2º Arbitration Act, 2003) – remain silent on this issue. In addition, it is perceived that some systems are opening the way to considering that the protection of confidential information is only pertinent when certain circumstances are met. There is, in this respect, a dialectical process between confidentiality and transparency that has especial repercussions in international commercial arbitration, particularly when one of the litigant parties is a State. Its sole presence can justify resorting to “public interest” and inclining the balance in favour of transparency.